Battery power may drain more quickly than you expect on a Windows Vista-based portable computer that has a USB SideShow-compatible device attached

Power management may not work correctly on a Windows Vista-based portable computer that has a Windows SideShow-compatible USB device attached. Because of this problem, the CPU may not correctly enter a reduced power-consumption state. In a reduced power-consumption state, the processor is supposed to conserve battery power. The processor does this by using reduced voltage or reduced frequency states. When this problem occurs, the battery may drain more quickly than you expect.

Service pack information

To resolve this problem, obtain the latest service pack for Windows Vista. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.Note After you install this hotfix, you must manually enable the USB selective suspend setting option. To do this, follow these steps:

1. Click Start
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   , type power options in the Start Search box, and then click Power Options in the Programs list.
   
   
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   If you are prompted for an administrator password or for a confirmation, type the password, or click Allow.
2. Under the selected power plan, click Change plan settings.
3. Click Change advanced power settings.
4. In the Power Options dialog box, expand USB settings, and then expand USB selective suspend setting.
5. If you want to enable Windows Vista to turn off the USB root hub when the computer is running on battery power, click Enabled in the On battery list.
6. If you want to enable Windows Vista to turn off the USB root hub when the computer is plugged into a power outlet, click Enabled in the Plugged in list, and then click OK.

Prerequisites

You must have the USB cumulative rollup for Windows Vista installed before you install this hotfix. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Vista, x86-based versions

Windows Vista, 64-bit versions

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows Vista Service Pack 1.

For more information, click the following article number to view the article in the Microsoft Knowledge Base: